An increase in the number of obese people has become a serious social problem in recent years. Obesity is a major cause of adult diseases such as diabetes and arteriosclerosis, and there is thus an earnest desire to reduce obesity.
In recent years attention has been focused oh the physiological actions of amino acids, and expectations have grown with respect to the antiobestic effect of amino acids. Among these, it has been reported that lysine, arginine, proline and phenylalanine have an antiobesity action and are referred to as diet amino acids, and, however, the grounds and effects thereof have not been sufficiently clarified. See T. Yamamoto (general supervising editor), “Amino Acids Diet”, published by Goma-shobo publishing Co., in 2002, and T. Sanjo (general supervising editor), “Amino Acids Diet”, published by Nitto-shoin publishing Co., in 2002.
Further, it has been reported that as a meal composition that exerts the maximum diet effect of amino acids, a ratio of protein:fat:carbohydrate is preferably 6:1:3. See T. Sanjo (general supervising editor), “Rapidly Get into Better Health with Amino Acids!!”, published by Mikasa-shobo publishing Co., in 2001. However, ingestion of this kind of high-protein diet is difficult from the practical viewpoint and, in addition, when a diet contains an extremely large amount of protein, the burden on the liver and the kidney is increased, and it cannot be considered desirable from the safety viewpoint. Therefore, there is a pressing need to clarify conditions that can ensure the safety of a composition as a food and also exert the effect to the fullest extent.
Meanwhile, the aforementioned problem of obesity has also been occurring in animals such as pets or zoo animals and other animals in recent years.